This invention relates to new chemical compounds, which are of value as new medicinal agents. More particularly, these new chemical compounds are phosphodiesterase inhibitors and cardiac stimulants of which a preferred class selectively increases the force of myocardial contraction without producing significant increases in heart rate. The compounds are useful in the curative or prophylactic treatment of cardiac conditions, in particular heart failure.
Published European Patent Application No. 0094766 and U.S. Pat. No. 4,489,075 provide inter alia novel cardiac-stimulating quinazoline compounds of the formula ##STR1## and their pharmaceutically acceptable salts;
wherein X is an alkylene group of the formula ##STR2## where R is H, CH.sub.3 or C.sub.2 H.sub.5 ;
and Y is a group of the formula: ##STR3##
where R.sup.1 is H or C.sub.1 -C.sub.4 alkyl;
and R.sup.2 and R.sup.3 are each independently H or CH.sub.3.
We have now discovered that derivatives of such compounds which contain a hydroxyl group attached either to the 3- or 4-carbon atom of the piperidine ring or to the carbon atom of X attached to the piperidine ring have particularly advantageous properties.